Sculpt a slab out of wood (5)
I believe the answer is:
balsa
'wood' is the definition.
(type of wood)
'sculpt a slab' is the wordplay.
'sculpt' indicates an anagram.
'a'+'slab'='aslab'
'aslab' anagrammed gives 'BALSA'.
'out of' acts as a link.
(Other definitions for balsa that I've seen before include "Tree with light soft wood" , "Something light" , "Strong lightweight wood" , "Tree yielding light wood" , "Central American forest tree used to make floats, rafts, models etc" .)